The advantages of certain optically anisotropic spinning solutions are shown in Blades U.S. Pat. No. 3,767,756. Solutions of polyhydrazides consisting essentially of repeating units ##STR1## in sulfuric acid (at least 99.5% concentration) or in mixtures thereof with up to 80% fluorosulfonic acid are isotropic. The present invention provides certain polyamide-hydrazides that do form optically anisotropic solutions in these solvent media.